Aquatic herb, rootless, submerged, except the inflorescence; free floating, slender stem, minutely hairy; leaves, alternate or 4 in whorls, 3-lobed or pinnately divided into narrow capillary segments, specifically insectivorous, small, bladders formed at their bases in whorls of 4-5 at the nodes to capture and digest tiny insects within the bladder; scape simple or branched; flowers 5-6 on slender, 10-20 cm long, erect, aerial racemes, held up by a whorl of spongy floats with filiform, external pinnules at their apices, pedicel bracteate, bracteoles absent; calyx 2 partite, ovate, enlarged in fruit; corolla yellow, bilipped, spur sub-cylindric, shorter than the lower lip, slightly curved, pubescent or glabrous; stamens 2, filaments broad, anthers ovate; ovary globose, 1-celled, ovules many, free central placentation, stigma usually 2-lobed, style short; capsule globose; seeds minute, very many thickly discoid with hardly winged margins.